Monolithic Macroporous Carbon Materials as High-Performance and Ultralow-Cost Sorbents for Efficiently Solving Organic Pollution

Carbon materials have shown great potential in solving environmental problems resulting from the pollution from oils or organic solvents. However, developing low-cost and high-performance carbon-based three-dimensional (3D) frameworks is still a great challenge and highly desired. Herein, monolithic macroporous carbon (MMC) materials have been synthesized through the pyrolysis of kapok wadding materials (ultralow-cost fibrous materials, those comprised of fibers with the highest hollow degree in nature). Owing to their unique and superior properties, such as tubular structure, light weight, high porosity, desirable flexibility, and strong thermal/mechanical stability, the MMC materials exhibit a high loading capacity for organic solvents and oils (87–273 times their own weight) and excellent recyclability. Coupled with the easy, economical, and environment-friendly synthesis process, MMC materials will be promising candidates for industrial application for removing organic pollutants. Hopefully, the MMC materials and the corresponding synthesis approach will be further applied to wider applications (e.g., energy storage, synthesis of composite materials, and so on)

Superhydrophobic Particles Derived from Nature-Inspired Polyphenol Chemistry for Liquid Marble Formation and Oil Spills Treatment

Nature has given us great inspirations to fabricate high-performance materials with extremely exquisite structures. Presently, particles with a superhydrophobic surface are prepared through nature-inspired polyphenol chemistry. Briefly, adhering of a typical polyphenol (tannic acid, widely existed in tea, red wine, chocolate, <i>etc</i>.) is first conducted on titania particles to form a multifunctional coating, which is further in charge of reducing Ag⁺ into Ag nanoparticles/nanoclusters (NPs/NCs) and responsible for grafting 1H,1H,2H,2H-perfluorodecanethiol, thus forming a lotus-leaf-mimic surface structure. The chemical/topological structure and superhydrophobic property of the as-engineered surface are characterized by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), energy dispersive spectroscopy (EDS), water contact angle measurements, and so on. On the basis of the hierarchical, superhydrophobic surface, the particles exhibit a fascinating capability to form liquid marble and show some possibility in the application of oil removal from water. After particles are <i>in situ</i> adhered onto melamine sponges, the acquired particle-functionalized sponge exhibits an absorption capacity of 73–175 times of its own weight for a series of oils/organic solvents and shows superior ease of recyclability, suggesting an impressive capability for treating oil spills

Superhydrophobic Particles Derived from Nature-Inspired Polyphenol Chemistry for Liquid Marble Formation and Oil Spills Treatment

Nature has given us great inspirations to fabricate high-performance materials with extremely exquisite structures. Presently, particles with a superhydrophobic surface are prepared through nature-inspired polyphenol chemistry. Briefly, adhering of a typical polyphenol (tannic acid, widely existed in tea, red wine, chocolate, <i>etc</i>.) is first conducted on titania particles to form a multifunctional coating, which is further in charge of reducing Ag⁺ into Ag nanoparticles/nanoclusters (NPs/NCs) and responsible for grafting 1H,1H,2H,2H-perfluorodecanethiol, thus forming a lotus-leaf-mimic surface structure. The chemical/topological structure and superhydrophobic property of the as-engineered surface are characterized by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), energy dispersive spectroscopy (EDS), water contact angle measurements, and so on. On the basis of the hierarchical, superhydrophobic surface, the particles exhibit a fascinating capability to form liquid marble and show some possibility in the application of oil removal from water. After particles are <i>in situ</i> adhered onto melamine sponges, the acquired particle-functionalized sponge exhibits an absorption capacity of 73–175 times of its own weight for a series of oils/organic solvents and shows superior ease of recyclability, suggesting an impressive capability for treating oil spills

Superhydrophobic Particles Derived from Nature-Inspired Polyphenol Chemistry for Liquid Marble Formation and Oil Spills Treatment

Nature has given us great inspirations to fabricate high-performance materials with extremely exquisite structures. Presently, particles with a superhydrophobic surface are prepared through nature-inspired polyphenol chemistry. Briefly, adhering of a typical polyphenol (tannic acid, widely existed in tea, red wine, chocolate, <i>etc</i>.) is first conducted on titania particles to form a multifunctional coating, which is further in charge of reducing Ag⁺ into Ag nanoparticles/nanoclusters (NPs/NCs) and responsible for grafting 1H,1H,2H,2H-perfluorodecanethiol, thus forming a lotus-leaf-mimic surface structure. The chemical/topological structure and superhydrophobic property of the as-engineered surface are characterized by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), energy dispersive spectroscopy (EDS), water contact angle measurements, and so on. On the basis of the hierarchical, superhydrophobic surface, the particles exhibit a fascinating capability to form liquid marble and show some possibility in the application of oil removal from water. After particles are <i>in situ</i> adhered onto melamine sponges, the acquired particle-functionalized sponge exhibits an absorption capacity of 73–175 times of its own weight for a series of oils/organic solvents and shows superior ease of recyclability, suggesting an impressive capability for treating oil spills

Fabrication of a Superhydrophobic, Fire-Resistant, and Mechanical Robust Sponge upon Polyphenol Chemistry for Efficiently Absorbing Oils/Organic Solvents

In this study, a superhydrophobic, fire-resistant, and mechanical robust sponge was fabricated through a two-step polyphenol chemistry strategy for efficiently absorbing oils/organic solvents (<i>rapidness in absorption rate and large quantity in absorption capacity</i>). Specifically, the Fe^(III)–polyphenol complex is formed upon the metal–organic coordination between tannic acid (TA, a typical polyphenol) and Fe^(III) ions, which is spontaneously coated on the surface of the pristine melamine sponge. Then, free catechol groups in the polyphenol are applied for grafting 1-dodecanethiol, thus generating the superhydrophobic sponge. Several characterizations have confirmed the chemical/topological structures, superhydrophobicity, fire-resistant merits, and mechanical robust property of the sponge. As a result, this sponge exhibits excellent absorption capacities of oils/organic solvents up to 69–176 times its own weight, indicating promising sorbents for removing oily pollutants from water. Meanwhile, owing to the facile fabrication process and inexpensive/easy available raw materials, the large-scale production of this sponge will be convenient and cost-effective

Facile Method To Prepare Microcapsules Inspired by Polyphenol Chemistry for Efficient Enzyme Immobilization

In this study, a method inspired by polyphenol chemistry is developed for the facile preparation of microcapsules under mild conditions. Specifically, the preparation process includes four steps: formation of the sacrificial template, generation of the polyphenol coating on the template surface, cross-linking of the polyphenol coating by cationic polymers, and removal of the template. Tannic acid (TA) is chosen as a representative polyphenol coating precursor for the preparation of microcapsules. The strong interfacial affinity of TA contributes to the formation of polyphenol coating through oxidative oligomerization, while the high reactivity of TA is in charge of reacting/cross-linking with cationic polymer polyethylenimine (PEI) through Schiff base/Michael addition reaction. The chemical/topological structures of the resultant microcapsules are simultaneously characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier Transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), <i>etc.</i> The wall thickness of the microcapsules could be tailored from 257 ± 20 nm to 486 ± 46 nm through changing the TA concentration. The microcapsules are then utilized for encapsulating glucose oxidase (GOD), and the immobilized enzyme exhibits desired catalytic activity and enhanced pH and thermal stabilities. Owing to the structural diversity and functional versatility of polyphenols, this study may offer a facile and generic method to prepare microcapsules and other kinds of functional porous materials

An Efficient, Recyclable, and Stable Immobilized Biocatalyst Based on Bioinspired Microcapsules-in-Hydrogel Scaffolds

Design and preparation of high-performance immobilized biocatalysts with exquisite structures and elucidation of their profound structure-performance relationship are highly desired for green and sustainable biotransformation processes. Learning from nature has been recognized as a shortcut to achieve such an impressive goal. Loose connective tissue, which is composed of hierarchically organized cells by extracellular matrix (ECM) and is recognized as an efficient catalytic system to ensure the ordered proceeding of metabolism, may offer an ideal prototype for preparing immobilized biocatalysts with high catalytic activity, recyclability, and stability. Inspired by the hierarchical structure of loose connective tissue, we prepared an immobilized biocatalyst enabled by microcapsules-in-hydrogel (MCH) scaffolds via biomimetic mineralization in agarose hydrogel. In brief, the in situ synthesized hybrid microcapsules encapsulated with glucose oxidase (GOD) are hierarchically organized by the fibrous framework of agarose hydrogel, where the fibers are intercalated into the capsule wall. The as-prepared immobilized biocatalyst shows structure-dependent catalytic performance. The porous hydrogel permits free diffusion of glucose molecules (diffusion coefficient: ∼6 × 10^–6 cm² s^–1, close to that in water) and retains the enzyme activity as much as possible after immobilization (initial reaction rate: 1.5 × 10^–2 mM min^–1). The monolithic macroscale of agarose hydrogel facilitates the easy recycling of the immobilized biocatalyst (only by using tweezers), which contributes to the nonactivity decline during the recycling test. The fiber-intercalating structure elevates the mechanical stability of the in situ synthesized hybrid microcapsules, which inhibits the leaching and enhances the stability of the encapsulated GOD, achieving immobilization efficiency of ∼95%. This study will, therefore, provide a generic method for the hierarchical organization of (bio)­active materials and the rational design of novel (bio)­catalysts

Preparation of Dopamine/Titania Hybrid Nanoparticles through Biomimetic Mineralization and Titanium(IV)–Catecholate Coordination for Enzyme Immobilization

In this study, a facile approach is proposed to prepare dopamine/titania hybrid nanoparticles (DTHNPs), which are synthesized via directly blending titanium­(IV) bis­(ammonium lactato) dihydroxide (Ti-BALDH) and dopamine aqueous solution. The amino group in dopamine is mainly in charge of inducing the hydrolysis and condensation of titanium precursor to form titania, and the catechol group in dopamine acts as an organic ligand to form titanium­(IV)–catecholate coordination. These DTHNPs were characterized by tranmission electron miscroscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The morphology of DTHNPs is changed from slightly cotton-shaped aggregates to monodisperse nanoparticles with the increase of dopamine concentration. As a model enzyme, catalase (CAT) is entrapped in the DTHNPs during the nanoparticle preparation process. Surprisingly, the entrapment efficiency of CAT can be high up to nearly 100%, and no enzyme leakage could be detected. Moreover, immobilized CAT possesses 90% the catalytic activity of free enzyme

Combination of Redox Assembly and Biomimetic Mineralization To Prepare Graphene-Based Composite Cellular Foams for Versatile Catalysis

Graphene-based materials with hierarchical structures and multifunctionality have gained much interest in a variety of applications. Herein, we report a facile, yet universal approach to prepare graphene-based composite cellular foams (GCCFs) through combination of redox assembly and biomimetic mineralization enabled by cationic polymers. Specifically, cationic polymers (e.g., polyethyleneimine, lysozyme, etc.) could not only reduce and simultaneously assemble graphene oxide (GO) into cellular foams but also confer the cellular foams with mineralization-inducing capability, enabling the formation of inorganic nanoparticles (e.g., silica, titania, silver, etc.). The GCCFs show highly porous structure and appropriate structural stability, where nanoparticles are well distributed on the surface of the reduced GO. Through altering polymer/inorganic pairs, a series of GCCFs are synthesized, which exhibit much enhanced catalytic performance in enzyme catalysis, heterogeneous chemical catalysis, and photocatalysis compared to nanoparticulate catalysts

Three-Dimensional Porous Aerogel Constructed by g‑C₃N₄ and Graphene Oxide Nanosheets with Excellent Visible-Light Photocatalytic Performance

It is curial to develop a high-efficient, low-cost visible-light responsive photocatalyst for the application in solar energy conversion and environment remediation. Here, a three-dimensional (3D) porous g-C₃N₄/graphene oxide aerogel (CNGA) has been prepared by the hydrothermal coassembly of two-dimensional g-C₃N₄ and graphene oxide (GO) nanosheets, in which g-C₃N₄ acts as an efficient photocatalyst, and GO supports the 3D framework and promotes the electron transfer simultaneously. In CNGA, the highly interconnected porous network renders numerous pathways for rapid mass transport, strong adsorption and multireflection of incident light; meanwhile, the large planar interface between g-C₃N₄ and GO nanosheets increases the active site and electron transfer rate. Consequently, the methyl orange removal ratio over the CNGA photocatalyst reaches up to 92% within 4 h, which is much higher than that of pure g-C₃N₄ (12%), 2D hybrid counterpart (30%) and most of representative g-C₃N₄-based photocatalysts. In addition, the dye is mostly decomposed into CO₂ under natural sunlight irradiation, and the catalyst can also be easily recycled from solution. Significantly, when utilized for CO₂ photoreduction, the optimized CNGA sample could reduce CO₂ into CO with a high yield of 23 mmol g^–1 (within 6 h), exhibiting about 2.3-fold increment compared to pure g-C₃N₄. The photocatalyst exploited in this study may become an attractive material in many environmental and energy related applications